1. Technical Field
The present invention relates to a technology for correcting images.
2. Related Art
In a projector, when the positional relationship between a screen and a projection system is deviated from an ideal state, the image projected on the screen is distorted. To cancel out this distortion, image processing of imparting a distortion opposite to the existing distortion to the input image is used. This image processing is performed for a pixel to be processed of the input image by referring to data of another pixel at a position designated by an offset vector corresponding to the pixel to be processed. In this case, when the components of the offset vector are not integers, the image processing is performed referring to data of four pixels around the position designated by the offset vector.
To perform image processing using data of four pixels, it is naturally required to read data of four pixels from a memory. That is, it is necessary to access one RAM four times, taking a time of four clocks to read the data. For example, in comparison with the case that the components of the offset vector are integers, it will take four times to read data, and the output of the image signal will be delayed by this long read time.
JP-A-10-336573 discloses a technique of accessing a memory at a clock rate double the image clock to generate a zoom image using data of two pixels in the vertical direction.
The above technique has a problem that the necessity of generating a high-speed clock increases the cost of the image processing circuit.